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      <title>微服务项目跨域问题怎么解决 - 交互式测验</title>
      <style>
        @import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@400;500;700&display=swap');
        
        body {
          font-family: 'Noto Sans SC', sans-serif;
          background-color: #f4f7f9;
          color: #333;
          display: flex;
          justify-content: center;
          align-items: center;
          min-height: 100vh;
          margin: 0;
          padding: 20px;
          box-sizing: border-box;
        }
        
        .main-wrapper {
            position: relative;
            width: 100%;
            max-width: 900px; /* Wider to accommodate buttons */
            display: flex;
            justify-content: center;
            align-items: center;
        }

        .quiz-container {
          background-color: #ffffff;
          border-radius: 16px;
          box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
          width: 100%;
          max-width: 700px;
          overflow: hidden;
          z-index: 10;
        }

        .quiz-header {
          background-color: #4a90e2;
          color: white;
          padding: 20px 30px;
          text-align: center;
        }

        .quiz-header h1 {
          margin: 0;
          font-size: 24px;
          font-weight: 700;
        }
        
        .quiz-header p {
            margin: 5px 0 0;
            font-size: 14px;
            opacity: 0.9;
        }

        .quiz-body {
          padding: 30px;
        }

        .progress-bar {
            display: none; /* 隐藏进度条 */
            width: 100%;
            background-color: #e0e0e0;
            border-radius: 5px;
            height: 10px;
            margin-bottom: 20px;
        }

        #progress-indicator {
            height: 100%;
            width: 0%;
            background-color: #4caf50;
            border-radius: 5px;
            transition: width 0.3s ease;
        }

        #question-container {
          margin-bottom: 20px;
        }

        #question-text {
          font-size: 18px;
          font-weight: 500;
          line-height: 1.6;
          margin-bottom: 25px;
        }

        .options-list {
          list-style: none;
          padding: 0;
          margin: 0;
        }

        .option-item {
          background-color: #f8f9fa;
          border: 1px solid #dee2e6;
          border-radius: 8px;
          padding: 15px;
          margin-bottom: 12px;
          cursor: pointer;
          transition: background-color 0.2s ease, border-color 0.2s ease;
        }

        .option-item:hover {
          background-color: #e9ecef;
        }
        
        .option-item.selected {
            background-color: #d1e7fd;
            border-color: #4a90e2;
        }

        .quiz-footer {
          padding: 20px 30px;
          display: flex;
          justify-content: space-between; /* 将按钮分布在两侧 */
          align-items: center;
          min-height: 65px; /* Reserve space */
        }

        .nav-btn {
          background-color: #4a90e2;
          color: white;
          border: none;
          border-radius: 8px;
          padding: 10px 20px;
          font-size: 16px;
          font-weight: 500;
          cursor: pointer;
          transition: background-color 0.2s ease, transform 0.2s ease;
          box-shadow: 0 4px 12px rgba(0,0,0,0.15);
        }
        
        #next-btn {
            background-color: #28a745;
        }

        .nav-btn:hover {
          background-color: #357abd;
          transform: scale(1.05);
        }
        
        .nav-btn:disabled {
            background-color: #a0c3e8;
            cursor: not-allowed;
            opacity: 0.7;
        }

        #result-container {
            border-top: 1px solid #eee;
        }
        
        .result-box {
            border-radius: 8px;
            padding: 20px;
            margin-top: 20px;
        }
        
        .result-box.correct {
            background-color: #d4edda;
            border: 1px solid #c3e6cb;
            color: #155724;
        }

        .result-box.incorrect {
            background-color: #f8d7da;
            border: 1px solid #f5c6cb;
            color: #721c24;
        }
        
        .result-box h3 {
            margin-top: 0;
        }

        .explanation-text {
            margin-top: 15px;
            line-height: 1.7;
        }
        
        .source-text {
            font-style: italic;
            font-size: 14px;
            margin-top: 15px;
            color: #555;
        }

        
        .final-score-container {
            padding: 40px;
            text-align: center;
        }
        .final-score-container h2 {
            margin-top: 0;
            margin-bottom: 30px;
        }
        .score-summary {
            display: flex;
            justify-content: center;
            gap: 20px;
            margin-bottom: 40px;
            flex-wrap: wrap;
        }
        .score-card {
            background-color: #f8f9fa;
            border-radius: 12px;
            padding: 20px;
            width: 180px;
            box-shadow: 0 4px 12px rgba(0,0,0,0.05);
            border: 1px solid #e9ecef;
        }
        .score-card h3 {
            margin: 0 0 10px;
            font-size: 16px;
            font-weight: 500;
            color: #555;
        }
        .score-card p {
            margin: 0;
            font-size: 28px;
            font-weight: 700;
            color: #333;
        }
        .score-details table {
            width: 100%;
            font-size: 16px;
        }
        .score-details td {
            padding: 4px 0;
        }
        .score-details td:last-child {
            text-align: right;
            font-weight: 700;
        }
        .report-actions button {
            background-color: #fff;
            border: 1px solid #ccc;
            border-radius: 8px;
            padding: 12px 25px;
            font-size: 16px;
            cursor: pointer;
            margin: 0 10px;
            transition: background-color 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
        }
        .report-actions button:hover {
            background-color: #f1f1f1;
            border-color: #bbb;
            transform: translateY(-2px);
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        .report-actions button.primary {
            background-color: #28a745;
            color: white;
            border-color: #28a745;
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        .report-actions button.primary:hover {
            background-color: #218838;
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        .hint-container {
            background-color: #e0f7fa;
            border: 1px solid #b2ebf2;
            border-radius: 8px;
            padding: 15px;
            margin-top: 20px;
            color: #006064;
            font-size: 15px;
            line-height: 1.6;
            display: none; /* 默认隐藏 */
        }
      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>微服务项目跨域问题怎么解决 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "在微服务架构中，使用API网关处理跨域请求相比于在每个服务中单独配置CORS，其主要优势是什么？",
    "options": [
      "它将所有HTTP请求转换为WebSocket连接，从而天然避免跨域问题。",
      "它通过反向代理，让所有服务看起来都与客户端同源。",
      "它完全不需要任何CORS配置，可以自动处理所有跨域请求。",
      "它可以集中管理和配置CORS策略，简化了对所有后端微服务的跨域管理。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "API网关作为所有请求的入口点，允许开发者在一个中心位置统一配置跨域规则。这样就不需要在每一个独立的微服务中重复配置CORS头部，大大简化了配置的复杂性和维护成本，提高了架构的整洁性。",
    "source": "文档中「2. 使用 API 网关」部分",
    "hint": "文档提到API网关可以“集中管理跨域请求”，思考一下“集中管理”带来的好处。"
  },
  {
    "question": "根据文档描述，JSONP（JSON with Padding）技术在解决跨域问题时存在一个非常显著的局限性，这个局限性是什么？",
    "options": [
      "它仅支持 GET 请求。",
      "它无法传输JSON格式的数据。",
      "它不被任何现代浏览器所支持。",
      "它要求服务器和客户端必须在同一个顶级域名下。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "JSONP的实现原理是利用 `<script>` 标签的 `src` 属性不受同源策略限制。由于 `src` 属性只能发起GET请求，因此JSONP天生就只支持GET方法，无法用于POST、PUT、DELETE等其他HTTP方法，这在现代需要复杂交互的Web应用中是一个巨大的限制。",
    "source": "文档中「4. JSONP（JSON with Padding）」部分",
    "hint": "文档中有一句关于JSONP的明确说明：“但它仅支持 GET 请求”。"
  },
  {
    "question": "反向代理（如Nginx）是如何从根本上“避免”浏览器产生跨域问题的？",
    "options": [
      "它强制所有客户端请求都使用JSONP格式进行通信。",
      "通过代理请求，使得客户端的请求目标地址与客户端页面处于同一个域下，从而绕过了浏览器的同源策略。",
      "它为每个跨域请求动态地向HTTP响应中添加CORS（跨源资源共享）头部。",
      "它将客户端和服务器之间的通信升级为WebSocket长连接。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "反向代理的核心作用是请求转发。当客户端访问 `api.example.com` 时，Nginx会将这个请求转发给后端的微服务（如 `service.example.com`）。对于浏览器来说，它始终是在和 `api.example.com` 这一个域名进行交互，因此不构成跨域请求，也就从根本上避免了同源策略的限制。",
    "source": "文档中「3. 使用反向代理」部分",
    "hint": "思考一下，当所有请求都指向同一个域名（如 `api.example.com`）时，浏览器还会认为这是跨域吗？"
  },
  {
    "question": "WebSocket技术之所以能用于解决跨域通信问题，其关键原因是什么？",
    "options": [
      "WebSocket协议在建立连接后，其后续的数据交换不受浏览器同源策略的限制。",
      "WebSocket天生只支持GET请求，这被浏览器认为是安全的。",
      "WebSocket强制要求所有通信都经过加密，因此浏览器会放行。",
      "WebSocket在每次通信时都会附带预检请求（preflight request）来获取服务器许可。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "WebSocket协议通过一个初始的HTTP握手请求来建立连接。一旦连接成功建立，它就会升级为一个持久化的、全双工的TCP连接。这个连接上的后续数据帧交换不再遵循HTTP的请求-响应模型，因此也不受浏览器同源策略的限制，允许客户端和服务器自由地双向通信。",
    "source": "文档中「5. WebSocket」部分",
    "hint": "文档描述WebSocket允许建立“持久的全双工通信通道”，这种通道与普通的HTTP请求有何不同？"
  },
  {
    "question": "在文档提供的Spring Boot CORS配置示例中，`.allowedMethods(\"GET\", \"POST\", \"PUT\", \"DELETE\")` 这行代码的作用是什么？",
    "options": [
      "指定服务器只接受来自特定IP地址的请求。",
      "允许跨域请求中包含哪些特定的HTTP头部。",
      "声明服务器允许哪些源（origin）发起跨域请求。",
      "指定服务器允许跨域请求使用的HTTP方法类型。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "CORS机制允许服务器精确控制跨域请求的权限。`.allowedMethods()` 方法就是用来声明服务器愿意接受哪些HTTP动词（如GET, POST等）的跨域请求。如果一个跨域请求使用了未在此处列出的方法（例如PATCH），浏览器将会阻止该请求。",
    "source": "文档中「1.1. 配置 CORS 头部」部分",
    "hint": "方法名 `allowedMethods` 直接揭示了它的用途。"
  },
  {
    "question": "CORS（跨源资源共享）机制的核心工作原理是怎样的？",
    "options": [
      "通过在服务器端设置特定的HTTP头部，来告知浏览器是否允许某个源的请求。",
      "通过动态创建`<script>`标签来加载不同域的资源。",
      "通过建立一个持久化的TCP连接，绕过HTTP协议的限制。",
      "通过API网关将所有请求伪装成同源请求。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "CORS是一种基于HTTP头的机制，它允许服务器在响应中包含一些特殊的头信息（如 `Access-Control-Allow-Origin`），从而授权指定的外部域访问其资源。浏览器在接收到响应后，会检查这些头部信息，如果当前域在许可范围内，则正常处理响应，否则会拦截响应。",
    "source": "文档中「1. 使用 CORS（跨源资源共享）」部分",
    "hint": "文档开篇就提到CORS“通过设置 HTTP 头部来允许特定的域访问资源”。"
  },
  {
    "question": "在众多跨域解决方案中，哪一种被认为是现代应用中更为主流、安全和灵活的选择，尤其是在需要支持多种HTTP方法（如GET, POST, PUT）时？",
    "options": [
      "JSONP",
      "WebSocket",
      "CORS",
      "反向代理"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档明确指出，JSONP的使用在现代应用中逐渐减少，因为CORS是“更为安全和灵活的解决方案”。CORS提供了对多种HTTP方法、自定义头部和凭证的精细控制，而JSONP仅限于GET请求。WebSocket和反向代理虽然也能解决问题，但CORS是专门为解决HTTP跨域资源访问而设计的W3C标准。",
    "source": "文档中「4. JSONP（JSON with Padding）」部分",
    "hint": "文档在介绍JSONP时，提到了哪一个方案是“更为安全和灵活的解决方案”？"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
        // 存储每个问题的回答状态
        const userAnswers = new Array(quizData.length).fill(null); 

        const questionTextEl = document.getElementById('question-text');
        const optionsListEl = document.getElementById('options-list');
        const resultContainerEl = document.getElementById('result-container');
        const quizContentEl = document.getElementById('quiz-content');
        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

        function loadQuestion() {
          resultContainerEl.innerHTML = '';
          optionsListEl.innerHTML = '';
          hintContainerEl.style.display = 'none'; // 隐藏提示
          
          if (currentQuestionIndex >= quizData.length) {
            showFinalScore();
            return;
          }

          updateProgress();

          const currentQuestion = quizData[currentQuestionIndex];
          questionTextEl.textContent = `(${currentQuestionIndex + 1}/${quizData.length}) ${currentQuestion.question}`;
          
          currentQuestion.options.forEach((optionText, index) => {
            const li = document.createElement('li');
            li.className = 'option-item';
            li.textContent = optionText;
            li.dataset.index = index; // Store index in a data attribute
            // 如果这道题已经回答过，恢复状态
            if (userAnswers[currentQuestionIndex] !== null) {
                if (index === userAnswers[currentQuestionIndex]) {
                    li.classList.add('selected');
                }
            }
            optionsListEl.appendChild(li);
          });

          // 如果已经回答过，直接显示结果
          if (userAnswers[currentQuestionIndex] !== null) {
              const isCorrect = userAnswers[currentQuestionIndex] === currentQuestion.correctAnswerIndex;
              showResult(isCorrect, currentQuestion);
          }
          
          updateNavigationButtons();
          updateProgress();
        }

        function selectOption(optionIndex) {
            userAnswers[currentQuestionIndex] = optionIndex;
            const currentQuestion = quizData[currentQuestionIndex];
            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
            score = userAnswers.reduce((acc, answer, index) => {
                return answer === quizData[index].correctAnswerIndex ? acc + 1 : acc;
            }, 0);

            showResult(isCorrect, currentQuestion);
            updateNavigationButtons();
        }
        
        function updateProgress() {
            const answeredQuestions = userAnswers.filter(answer => answer !== null).length;
            const progressPercentage = (answeredQuestions / quizData.length) * 100;
            progressIndicatorEl.style.width = `${progressPercentage}%`;
        }
        
        function updateNavigationButtons() {
            prevBtn.style.display = 'block';
            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

            prevBtn.disabled = currentQuestionIndex === 0;
            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
            nextBtn.textContent = (currentQuestionIndex === quizData.length - 1) ? '查看报告' : '下一题';
            
            // 如果当前问题没有提示，则禁用提示按钮并隐藏提示内容
            if (!quizData[currentQuestionIndex].hint) {
                hintBtn.disabled = true;
                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
            } else {
                hintBtn.disabled = false;
            }
        }

        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
            resultContainerEl.appendChild(resultBox);

            // 禁用所有选项的点击事件，并高亮正确/错误答案
            Array.from(optionsListEl.children).forEach((child, index) => {
                child.style.pointerEvents = 'none';
                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
                }
            });
        }

        function goToNextQuestion() {
            if (currentQuestionIndex < quizData.length - 1) {
                currentQuestionIndex++;
                loadQuestion();
            } else {
                showFinalScore();
            }
        }

        function goToPreviousQuestion() {
            if (currentQuestionIndex > 0) {
                currentQuestionIndex--;
                loadQuestion();
            }
        }
        
        function showHint() {
            const currentQuestion = quizData[currentQuestionIndex];
            if (currentQuestion.hint) {
                hintContainerEl.textContent = currentQuestion.hint;
                hintContainerEl.style.display = 'block';
            } else {
                hintContainerEl.style.display = 'none';
            }
        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  